Connections are a way for you to link people, places or groups (what we call entities) together. Connections can be customized with the relevant information for the unique relationship. The most common usages for Connections allow you to relate people to people or people to an employer. For a person to person connection, you can add fields to track how long they've known each other, what type of relationship they have and any notes that are important to know. For a person to an employer, you can add fields about their Job Title, Department, Shift, etc.
Connections are customized and added to campaigns by your organizations Admin(s). Because of this, you may not see connections available if they haven't been set up in your campaign. If you have questions about the fields available in your campaign, contact your campaign admin for more information.